BITS Faculty Publications
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Item Thermal-hydraulic characteristics and performance of 3D straight channel based printed circuit heat exchanger(Elsevier, 2016-04) Aneesh, A.M.CFD study is done to propose an efficient PCHE (Printed Circuit Heat Exchanger) model; used as a recuperator in International Thermonuclear Experimental Reactor (ITER). 3D steady-state conjugate heat-transfer simulations are done with helium as a working fluid and alloy 617 as the solid substrate. Effect of variation of thermo-physical properties, operating conditions and three different design modifications are studied. Thermal hydraulic performance is found better for single as compared to double banking and is the same for aligned as compared to the staggered arrangement of the hot and cold channels. PCHE models with hemispherical dimples are found to give better thermal hydraulic performance. The performance is presented for the variation of the heat transfer density (for a PCHE model) and the pressure drop (in the hot and cold channel). Various types of flow patterns are presented to analyze the thermal-hydraulic characteristics − leading to the heat transfer enhancement by the dimples.Item Thermal-hydraulic characteristics and performance of 3D wavy channel based printed circuit heat exchanger(Elsevier, 2015-08) Aneesh, A.M.CFD study is done here to propose an efficient PCHE (Printed Circuit Heat Exchanger) model; used as a recuperator in International Thermonuclear Experimental Reactor (ITER). 3D steady state conjugate heat-transfer numerical simulations are done; considering the variation of thermo-physical properties as a function of temperature. Helium is used as a working fluid and alloy 617 as solid substrate. The study is done for various angle of bend (θ = 0°(straight), 5°, 10° and 15°) and Reynolds number (Re = 350, 700, 1400 and 2100). Various types of flow patterns, within one wavy-section, are presented to analyze thermal-hydraulic characteristics. Thermal hydraulic performance parameters are presented for the various wavy-sections as well as within a section; and for the complete PCHE model. Heat transfer enhancement as compared to pressure penalty is higher for the wavy channel; and increases with increasing Re and θ. Wavy as compared to plane channel based PCHE is demonstrated here to give better thermal-hydraulic performance. A detailed characteristics as well as performance-parameters for thermal hydraulics in a 3D wavy channel based PCHE model − not found in the literature − is presented here.Item Effects of wavy channel configurations on thermal-hydraulic characteristics of Printed Circuit Heat Exchanger (PCHE)(Elsevier, 2018-03) Aneesh, A.M.Printed Circuit Heat Exchanger (PCHE) is a widely chosen plate type compact heat exchanger for high pressure applications. The present work mainly focuses on two high pressure applications; firstly, Helium Cooling System (HCS) of Test Blanket Module (TBM) in International Thermonuclear Experimental Reactor (ITER) and secondly, Intermediate Heat exchangers (IHX) in Very High Temperature Reactors (VHTR). In this work, a reduced numerical model for a single banked PCHE core working in He-He counter flow circuit has been numerically modelled and verified against the results available in the literature. The same model is then extended for studying the effect of three wavy-channel configurations viz. triangular, sinusoidal and trapezoidal in a single banked PCHE core made of Alloy-617. The nature of local flow and heat transfer in the periodic channels has been studied by visualizing the vortex core using iso-normalized helicity surfaces. Thereafter, the thermo-hydraulic performances of these models are compared with straight channel PCHEs. Among the various models studied, the trapezoidal PCHE model is found to offer highest heat transfer with the largest pressure drop compared to sinusoidal, triangular and straight channel based PCHE models. A maximum of 41% increase in the heat transfer rate is predicted for the trapezoidal wavy channel compared to the straight channel PCHEs, for the tested operating conditions. For the sinusoidal and triangular wavy-channel PCHE configurations, the corresponding heat transfer advantages are predicted to be 33% and 28% respectively. The optimal thermo-hydraulic performance is also assessed, considering the thermal performance factor (TPF) obtained for all the three channels. The highest values of TPF are predicted for trapezoidal wavy channels (3.5) which is followed by sinusoidal (2.5) and triangular (1.5) wavy channels.